The La Plata dolphin or Franciscana – Toninha (Pontoporia blainvillei) is one of the smallest dolphin species, with a maximum body length of 1.70 m and a body weight of 45 kg. In Brazil, it is called Toninha. It has a gray-brown coloration, with the back usually slightly darker than the belly. Its head is very round and its beak is exceptionally slender and long. In relation to its body length, it has the longest beak of all dolphin species. Its fin is triangular with a rounded tip and is well developed compared to other river dolphin species. Its flippers are extremely broad.
Although belonging to the river dolphin family, the La Plata dolphin is predominantly a marine species. Its range is limited to the coastal areas of South America's Atlantic waters from Espirito Santo, Brazil, to the Valdez Peninsula, Argentina. The animals prefer shallow coastal waters and are rarely seen in waters deeper than 20 meters.
In terms of behavior, La Plata dolphins are rather shy and inconspicuous and do not perform the acrobatic jumps typical of many dolphin species. They live in small groups of up to five animals, but are usually only sighted as solitary animals. The gestation period is approximately 10 to 11 months. Calves are mainly born between November and January and are then suckled by their mothers for around 9 months. La Plata dolphins often swim on their backs or on their sides. This behavior has also been observed in other river dolphins and is associated with the animals' echolocation behavior. Due to the direction of the echolocation clicks (dorso-frontal) and the dolphins' foraging behavior, this swimming position is extremely useful for locating prey on the sea or river bed.
dangers
Since the La Plata dolphin – Franciscana – Toninha (Pontoporia blainvillei) lives mainly near the coast, it is particularly sensitive to anthropogenic influences. Increasing water pollution from toxic chemicals and the regional fishing industry have severely reduced the population in recent decades. Coastal fishing and the resulting high number of bycatch victims are particularly worrying. Overfishing of its prey fish has already driven the La Plata dolphin out of some areas of its original range.
The Franciscana dolphin – Toninha – is now the most endangered dolphin species in South America.
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